Rapid identification of antibiotic residues in bovine kidney using coated blade spray-mass spectrometry

The use of certain antibiotics in food-producing animals is allowed in Europe following Regulation (EU) 2017/625. However, use could result in antibiotic residues in foodstuffs of animal origin. Maximum residue limits (MRLs) are in place to protect consumers. For monitoring purposes, animal matrices are tested to verify their compliance with these MRLs. Initially, matrices of (slaughtered) food animals are screened, often using a microbiological assay. Faster screening tests for antibiotics would be an advantage for control laboratories. Therefore, the present study describes, for the first time, the use of coated blade spray (CBS) followed by direct mass spectrometry (MS) analysis for the screening of tetracyclines, sulfonamides, quinolones, and macrolides residues from the renal area of intact bovine kidneys. An optimized workflow using two different desorption/ionization solutions per blade allowed screening of target compounds within 1 min per sample. The proof-of-principle of the CBS-MS method is validated according to (EU) 2021/808, presenting CCβ screening values of 0.1 × MRL for 43 analytes, 0.5 × MRL for 4 analytes, and 2.5 µg kg⁻¹ for the prohibited substance dapsone, respectively. The developed method was successfully applied to seven official control samples of bovine kidneys. One of these samples was found to be positive using the CBS-MS method, which was confirmed as a true positive by LC-MSMS analysis. The developed method demonstrates that CBS devices can directly extract and analyze kidney samples for food safety testing.